1. Field of the Invention
The invention relates to a drive device, a hybrid vehicle equipped with the drive device, and a control method for the drive device.
2. Description of the Related Art
A drive device that raises the operating voltage of a capacitor if the device detects a low temperature that increases the internal resistance of the capacitor has been proposed (e.g., see Japanese Patent Application Publication No. 2002-142373 (JP-A-2002-142373)). In this device, raising the operating voltage of the capacitor when the temperature is low compensate for the reduction of the amount of electricity stored in the capacitor caused by the increase of the internal resistance when the temperature is low.
Besides, a device that warms a battery by actively charging or discharging the battery when the temperature of the battery is low has also been proposed (e.g., see Japanese Patent Application Publication No. 2000-40536 (JP-A-2000-40536)). In this device, the warm up of the battery is performed by the internal heat generation that occurs when the battery is charged or discharged.
In a drive device that uses a plurality of capacitors connected in parallel with a motor, it is desired to quickly warm up the capacitors during the system start-up since the capacitor internal resistance is large due to low temperature. For such an occasion, it is conceivable to actively charge and discharge the capacitors. However, this often ends up with the unnecessary driving of the motor, or requires a special circuit for actively charging and discharging the capacitors.